EP0885537A4

EP0885537A4 - System and method for selecting a desired service provider

Info

Publication number: EP0885537A4
Application number: EP97917912A
Authority: EP
Inventors: Steven R Donovan
Original assignee: MCI Communications Corp
Current assignee: MCI Communications Corp
Priority date: 1996-04-10
Filing date: 1997-04-10
Publication date: 2001-09-05
Also published as: JP2001521682A; CA2250787A1; WO1997038539A1; EP0885537A1

Abstract

A system and method for determining whether a subscriber's desired service provider is operating on a band of the spectrum in a subscriber's current geographic area provides service when that subscriber is roaming out of his or her home geographic area. When service in a new geographic area is initiated (204), a check is made to determine whether this default service provider is a desired service provider (212). If the default service provider is a desired service provider, the service request is granted and the subscriber is free to place and receive calls (216).

Description

System and Method for Selecting A Desired Service Provider

Background of the Invention

1. Field of the Invention

This invention relates generally to wireless communication systems and more specifically to a system and method for selecting a desired service provider in a wireless communication system.

2. RelatedArt

The first generation of cellular technology, advanced mobile phone system (AMPS) has enjoyed much success in the telecommunications industry. In fact, AMPS has become so successful that demands for its service are far exceeding the available capacity in certain metropolitan areas.

New technologies for personal communications are emerging to take advantage of the high demand for mobile communications and to attempt to offer enhanced services and/or performance. One such new technology is the Personal Communications Services (PCS). Several systems have been implemented to provide PCS functionality. One common service is the CT-2 (cordless telephone 2) service which is being adopted as a standard in many countries.

Whether the technology is AMPS or PCS, the equipment and service provider market is primarily dominated by a handful of vendors. However, as demands increase new players continue to enter the market to offer products and services. To allow multiple carriers to share the available communications bandwidth, the spectrum is divided and allocated among the various carriers. For example, in current AMPS implementations the frequency spectrum is divided into two frequency bands. These are referred to as the A-side and B-side of the frequency spectrum. For PCS, it is envisioned that the spectrum be divided into 6 different frequency bands referred to as A, B, C, D, E, and F bands.

One recent phenomenon beginning to emerge among vendors is the reseller service provider. A service reseller planning to enter the communications market purchases communications services from a primary provider and re-sells the service to its own customers, or subscribers.

Typically, as a mobile subscriber travels (or "roams") from one cell to the next, his or her service is handed off to the carrier in the new cell. Traditionally, the carrier used by the subscriber occupies the same portion of the frequency spectrum from cell to cell. Therefore, as the subscriber roams to a new cell, there is no need to change the operating frequency of the subscriber's mobile telephone.

However, where the service provider is a reseller company, the service provider may have arrangements with different carriers in different geographic areas. Therefore, as the subscriber of the reseller provider moves from one region to the next, the primary carrier may change and so may the portion of the frequency spectrum allocated to handle the subscriber's call.

When this occurs, the subscriber has to manually switch the frequency to the correct band that is used by the carrier in the new region. This may be accomplished by the subscriber manually reprogramming his or her telephone (also referred to as mobile terminal, or mobile telephone terminal). Summary of the Invention

The present invention is directed toward a system and method for determining whether a subscriber's desired service provider is operating on a side of the spectrum in a subscriber's current geographic area when that subscriber is roaming out of his or her home geographic area.

When roaming outside of his or her home geographic area, the subscriber initiates a service request to a service provider in his or her current geographic area. This request can be made by powering up the mobile telephone or initiating a telephone call. This request is, by default, made to the service provider in the current geographic area servicing the side of the spectrum on which the subscriber typically operates. This service provider is referred to as the default service provider.

First, a check is made to determine whether this default service provider is a desired service provider. That is, it is determined whether the default service provider is either the same as the desired service provider or whether the default service provider has a service agreement with the reseller through which the subscriber obtains service.

If the default service provider is a desired service provider, the service request is granted and the subscriber is free to place and receive calls. If, on the other hand, the default service provider is not a desired service provider, it is determined whether a desired service provider is available on another band of the spectrum in the current geographic area.

If a desired service provider is not available on another band of the spectrum in the current geographic area, the subscriber is provided the option of continuing service with the default service provider. If, however, a desired service provider is available on another band of the spectrum in the current geographic area the subscriber (and/or his or her mobile telephone) is so notified. A message or other such indication is provided indicating that the a desired service provider is available on another band of the spectrum in the current geographic area. The message can inform the subscriber to switch bands, or the message can inform the subscriber's telephone to switch bands so that the subscriber need not take any special steps to obtain service.

An advantage of the invention is that the subscriber can obtain service from a desired service provider in a foreign (i.e., away from home) geographic area without having to take any special action. The subscriber need not reprogram his or her mobile phone. Further, the subscriber does not even need to know that the change has been made and the subscriber does not need to keep track of service providers in various roaming areas.

Another advantage is that when the subscriber roams from one geographic area to the next while engaged in a communication, the change can be made without a disruption of service to the communication.

Further features and advantages of the present invention, as well as the structure and operation of various embodiments of the present invention, are described in detail below with reference to the accompanying drawings.

Brief Description of the Drawings

The present invention is described with reference to the accompanying drawings. In the drawings, like reference numbers indicate identical or functionally similar elements. Additionally, the left-most digit of a reference number identifies the drawing in which the reference number first appears.

FIG. 1 is a diagram illustrating an example environment of the invention.

FIG. 2 is an operational flow diagram illustrating a process by which a desired service provider is selected according to one embodiment of the invention.

FIG. 3 is an operational flow diagram illustrating a process by which a home location register determines whether a desired service provider is available according to one embodiment of the invention.

FIG. 4 is an operational flow diagram illustrating a process by which the mobile telephone automatically accesses the desired service provider according to one embodiment of the invention.

Detailed Description of the Embodiments

1. Overview and Discussion of the Invention

The present invention is directed toward a system and method for selecting a subscriber's desired service provider in a wireless communication system, such as a cellular communication system. More specifically, the system and method provides the subscriber with service by his or her desired service provider regardless of the side of the spectrum on which that provider is operating in the subscriber's current geographic area

According to the invention, a system and method determines whether the subscriber is requesting service from a desired wireless service provider in the subscriber's current geographic area. If so, the service request is registered. If not, the system and method determines whether the service is available from the desired service provider on a different side of the spectrum. The manner in which this is accomplished is described in detail below.

2. Example Environment

Before describing the invention in great detail, it is useful to describe an example environment in which the invention can be implemented. In the broadest sense, the invention can be implemented in any wireless communication network where channel or frequency band selection needs to be done. One example of such a wireless communication network is a cellular telephone communication network, an example of which is the well known advanced mobile phone system (AMPS). Another example is the personal communication system cellular network.

FIG. 1 is a block diagram illustrating a typical wireless telecommunication network 100 that can serve as an example environment of the invention. The telecommunication network 100 includes cell sites 102, cell site controllers 104, mobile switches 106, home location register 108, radio trunk groups 111, and signaling links 1 12. Subscribers communicate via this network 100 using mobile telephone terminals 110 (e.g., cellular phones in this environment) which preferably interface to the network 100 via an air interface 114.

Each cell site 102 includes a radio transmitter that covers a particular area for that cell site 102. The call coverage area for a given cell site 102 is the area in which a subscriber can access the telecommunications network 100 by that particular cell site 102.

Associated with one or more cell sites 102 is a cell site controller 104

(sometimes referred to as a base station controller). One function of the cell site controller 104 is to determine the call coverage area for each associated cell site 102. In addition to determining coverage area, the cell site controllers 104 are responsible for monitoring each of their associated cell sites 102. Cell site controllers 104 also calculate the resource capacity for the network elements they control such as associated cell sites 102 and trunk groups 111 (described below).

The group including the cell site controller and its associated cell sites 102 is usually referred to a mobile subscriber group (MSG). Several MSGs connected to a mobile switch 106 are referred to as a base station subsystem.

A group of one or more cell site controllers 104 is controlled and monitored by mobile switch 106 (sometimes referred to as a mobile services switching center, or MSC). Mobile switch 106 is a switch or a switching system that provides communication paths to other networks. For example, mobile switch 106 can communicate with another telecommunications network such as a public switched telephone network (PSTN).

Mobile switch 106 can also be used to calculate resource capacity and

HDSIA data for the associated cell site controllers 104. Mobile switch 106 can also include a visitor location register (VLR) to store information mobile subscribers that roam into its coverage area.

The entire telecommunications network 100 is monitored and controlled by home location register 108. Home location register 108 is a database that contains information concerning the mobile subscriber such as their access capabilities, subscribed services and supplementary services. Home location register 108 can determine the coverage area for each of the cell sites 102 in the entire network 100, keep track of traffic in the telecommunications network 100, and maintain a record of the status of telecommunications network 100. The home location register 108 can also calculate resource capacity and HDSIA data for the mobile switches 106 that it controls.

Communication between the various network elements described above occurs over trunk groups 111 and signaling links 112. Trunk groups 111 transmit call traffic between the various elements of the telecommunications network 100.

Each trunk group 111 can transmit one or more calls over one or more trunk lines

(not shown).

The signaling links 112 transmit control and status information between the various network elements of telecommunications network 100. Control information includes cell site configuration such as coverage area. Status information includes alarm data as described above. An example of a signaling link 1 12 is an SS7 (signaling system 7) signaling link.

A subscriber can communicate using the telecommunications network 100 via a mobile phone (or a mobile telephone terminal) such as the mobile phones 110. The communication path can be an air interface such as the air interfaces 1 14. When a subscriber makes a call, a connection is established between the subscriber's particular mobile phone 1 10 and a particular cell site 102 via air interface 1 14.

For AMPS cellular networks, the spectrum allocated by the FCC has a bandwidth of 50MHz. This spectrum is divided into two equal parts, referred to as system A and system B. System A and B each have an allocation of 416 frequency pairs with 30kHz channel spacing.

The present invention is described in terms of this example environment.

Specifically, the invention is described in terms of an AMPS network having a spectrum divided into two sides, or bands: the A-side and the B-side. Description in these terms is provided for convenience and ease of description only. It is not intended that the invention be limited to application in this example environment. In fact, after reading the following description, it will become apparent to a person skilled in the relevant art how to implement the invention in alternative environments such as an AMPS environment having more than two bands, the PCS environment, or in other communication networks.

3. Embodiments of the Invention

As stated above, both the AMPS and the PCS provide a spectrum that is divided into bands (referred to as A-side and B-side for current AMPS networks). Each band is handled by a designated service provider. The subscriber's mobile phone 110 is configured to access the subscriber's desired service provider on one side of the spectrum. Thus, if the subscriber's desired service provider is on the A-side of the spectrum for example, that subscriber's mobile phone 1 10 attempts to connect to the A-side of the spectrum regardless of the area from which the call is made.

However, where the subscriber's service provider is a reseller, a subscriber's desired service provider may change from one area to the next.

Thus, when that subscriber roams to a different geographic area, he or she may need to access a different side of the spectrum to reach his or her desired service provider.

Traditionally, this had been done by requiring the subscriber to 'reprogram' his or her mobile phone 110 to access the other side of the spectrum. Thus, for example, with a conventional network, when a subscriber whose home carrier (desired service provider) is on the A-side roams to an area where the desired service provider is on the B-side, the subscriber must reprogram his or her mobile phone 1 10. If the subscriber does not reprogram mobile phone 110, service will be provided by a carrier other than the desired service provider, and perhaps at substantially increased rates. This other carrier is referred to as a "foreign service provider" in this document.

According to the invention, a system and method are provided for automatically reprogramming the subscriber's mobile phone 110 to access the correct side of the spectrum, regardless of whether the correct side is different from the side on which the subscriber's usual designated service provider operates. In this section of the document, several alternative embodiments are presented and described.

FIG. 2 is an operational flow diagram illustrating a process according to one embodiment of the invention by which a subscriber's desired service provider is accessed regardless of the side of the spectrum on which the desired service provider is operating. In a step 204, the subscriber initiates a service request of the communications network (e.g., of network 100). This request can be initiated by subscriber turning on mobile phone 110, originating a phone call using mobile phone 110, entering a new geographic area, or other like action.

In a step 208, mobile telephone 1 10 requests access on the subscriber's home side of the spectrum. That is, the request is made on the side of the spectrum on which the subscriber's phone normally operates when the subscriber is in his or her normal, or home, geographic area. This request results in a service request to the service provider which provides service on that side of the spectrum in the subscriber's current geographic area. This service provider is referred to as a "default service provider" throughout this document.

Depending on the arrangements that the reseller has with the default service provider, the default service provider may or may not be the desired service provider for the geographic area from which subscriber is placing this call. In a step 212, it is determined whether the default service provider is the subscriber's desired service provider. In one embodiment, this is accomplished by determining whether the desired service provider is operating on the side of the spectrum on which service was requested in the current geographic area. This can be accomplished by using the subscriber's ID as a key to lookup service provider information in a database

In another embodiment, this is accomplished by determining the identification of the default service provider and determining whether the default service provider is a desired service provider. One way of doing this is by doing a lookup using a list of desired service providers for the subscriber.

If the default service provider is the subscriber's desired service provider, service is granted as illustrated by a step 216 and normal registration actions are taken by home location register 108.

If, on the other hand, the default service provider is not the subscriber's desired service provider, it is determined whether a desired service provider exists on another side of the spectrum. This is illustrated by a step 220. If a desired service provider is not available on another side of the spectrum, access is granted to the default service provider and normal registration actions are taken by the home location register 108.

If, however, a desired service provider is available on another side of the spectrum in the subscribers current geographic area, a message is sent to the subscriber instructing him or her to change to the side of the spectrum on which the desired service provider is operating. This is illustrated by a step 228. In one embodiment of step 228, the subscriber is required to reprogram the phone to operate on the desired side of the spectrum. In this embodiment, the subscriber can be notified using audio, alphanumeric text (such as textual short message) or other technique to inform the subscriber of the correct side of the spectrum.

In another embodiment of step 228, the process is automated so that the subscriber need not take any specific action. In one embodiment of this automated process, mobile phone 110 is instructed to change to the side of the spectrum on which the desired service provider is operating. This can be accomplished by sending an instruction, command or other message to the subscriber's mobile phone 110 instructing mobile phone 110 to switch sides. This can be accomplished using CDMA (Code Division Multiple Access) over- the-air activation, TDMA (Time Division Multple Access) over-the-air activation, GSM USSD (Group Speciale Mobile Unstructured Supplementary Service Data), or short message teleadmin techniques, as well as by other techniques.

In response to the instruction sent in step 228, subscriber's mobile phone

110 resets the default service provider (i.e., the default side of the spectrum) to the side on which the desired service provider is available. This occurs in a step

232. Where required, mobile phone 110 initiates a new access through the available desired service provider.

In one embodiment, the process described above is accomplished using additional information available at the subscriber's home HLR. In this embodiment, information such as desired carriers, mobile switch IDs, spectrum indicators and other information can be used to determine whether the default carrier is a desired service provider and, if not, whether a desired service provider is available in the geographic area.

In one embodiment, when the subscriber initiates service in a foreign geographic area (i.e., a geographic area other than the subscriber's home geographic area), a notification message is sent to the home location register 108 serving the subscriber's home area. Included in this message is an identification of the service provider available to serve the subscriber in the current geographic area. In one embodiment, this identification is made using a mobile switch ID or other indication that can be used to determine the service provider identification. Home location register 108 determines whether this available service provider is a desired service provider. In one embodiment, this is accomplished by comparing this identification to a list of desired service providers.

Where the default service provider is not a desired service provider, home location register 108 determines whether there is a desired service provider in that geographic area and, if so, the side of the spectrum on which it operates. In one embodiment, this is accomplished by a simple table lookup.

The process used by home location register 108 in these embodiments is now described with reference to FIG. 3. In a step 304, the mobile switch identification is determined from the message. In one embodiment this is accomplished by retrieving the record containing the mobile switch ID from the message. In one embodiment, if the record is not found, an error condition exists and the process halts.

In a step 308, the mobile switch ID is used to determine whether the service provider is a desired service provider. In one embodiment, this is accomplished by determining the identity of the default service provider from the mobile switch ID and then comparing this identity with the desired service provider (or by simply comparing ID's). If the service provider identified by the mobile switch ID is a desired service provider, then the process is completed and registration can continue as normal as illustrated by step 312.

If, the identified service provider is not a desired service provider, home location register 108 checks its database to determine whether a service provider on another side of the spectrum is a desired service provider. This is illustrated by a step 316. In an embodiment where there are only two sides to the spectrum and only one service provider per side, this can be a simple boolean indicator of whether the other service provider is a desired service provider. Where there is a desired service provider on another side of the spectrum, the subscriber (or the subscriber's mobile phone 110 in an automated embodiment), is notified to change to that side of the spectrum.

If a desired service provider does not exist in that geographic area, a notification is sent to the subscriber to indicate this. The notification process can be accomplished according to a number of different embodiments. In one embodiment, a call is placed to the subscriber notifying him or her that only a foreign service provider is available and this may result in additional charges for the service. This can be done using a voice call that plays scripts to the subscriber stating that the only service provider is a foreign service provider, or by using alphanumeric signals that can be displayed on an alphanumeric display on mobile telephone 110. Alternatively, a command can be sent to mobile telephone 110 to provide an indication via mobile phone 110 that the only service provider available is a foreign service provider. This indication can include, for example, an indicator light, a display flag on a display screen of mobile phone 110, a specific tone, or other indication.

In another embodiment, the notification process can include instructions on how to register with the foreign service provider. In this case, the subscriber has the choice of not making any calls, paying higher prices to a foreign service provider, or registering with the foreign service provider before making a call.

Although the process is described above as being performed by the home location register 108, it could easily be performed by a physically or logically separate entity. In these embodiments, the separate entity may use data already existing in home location register 208 to avoid unnecessary duplication and maintenance of data.

In other alternative embodiments, determination and selection of the desired service provider is accomplished by a mobile phone search of the spectrum. FIG. 4 is a diagram illustrating a process by which this selection is made according to one embodiment. In a step 404, the subscriber initates a service request of the communications network (e.g., of network 100). This request can be initiated by subscriber turning on mobile phone 110, originating a phone call using mobile phone 110, entering a new geographic area, or other like action.

In a step 408, mobile telephone 1 10 requests access with the default wireless service provider. In other words, mobile telephone requests access with the wireless service provider that is normally used by the subscriber in the subscriber's home territory. Depending on the arrangements that the reseller has with the default service provider, the default service provider may or may not be the desired service provider for the geographic area from which subscriber is placing this call.

In a step 412, it is determined whether the default service provider is the subscriber's desired service provider. If the default service provider is the subscriber's desired service provider, service is granted and normal registration actions are taken by home location register 108. This is illustrated by a step 424.

If, on the other hand, the default service provider is not the subscriber's desired service provider, mobile telephone 1 10 automatically changes to a different side of the spectrum and the process conducted in steps 408 and 412 is repeated. This time, in step 408, the request is not made to the default, but instead is made to the service provider on the current side of the spectrum. This -16- process is repeated for each side of the spectrum until a side is accessed on which a desired service provider operates. This is illustrated by steps 416 and 420 and flow line 462.

If there is no available desired service provider after all sides of the spectrum are investigated, in a step 428 the subscriber is notified that only foreign service providers are available. This process is similar to that described above with reference to FIG. 2, steps 228 and 232.

3. Conclusion

While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not limitation. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.

Claims

In the Claims:

1. In a wireless communication system operating in a spectrum having at least two sides, each side having a service provider operating thereon, a system for providing service to a roaming subscriber in a current geographic area outside of a home area of the subscriber, the system comprising: means for determining whether a desired service provider of the subscriber operates on the side of the spectrum accessed by the subscriber; means for determining whether said desired service provider operates on any other side of the spectrum in the current geographic area; and means for providing service to the subscriber via the desired service provider if the desired service provider is available in the current geographic area.

2. The system of claim 1 , wherein said means for providing service to the subscriber via the desired service provider comprises means notifying the subscriber that the desired service provider is operating on a different side of the spectrum.

3. The system of claim 2, wherein said means for notifying the subscriber comprises means for sending a message to the subscriber indicating on which side of the spectrum said desired service provider is operating.

4. The system of claim 2, wherein said means for notifying the subscriber comprises means for sending an audio message to the subscriber notifying the subscriber that the desired service provider is operating on a different side of the spectrum.

5. The system of claim 2, wherein said means for notifying the subscriber comprises means for sending an alphanumeric text message to the subscriber notifying the subscriber that the desired service provider is operating on a different side of the spectrum.

6. The system of claim 1, wherein said means for providing service to the subscriber via the desired service provider comprises means for commanding the subscriber's mobile telephone to switch to the side of the spectrum on which said desired service provider is operating.

7. The system of claim 6, wherein said means for commanding the subscriber's mobile telephone to switch to the side of the spectrum on which said desired service provider is operating, comprises means for sending a CDMA over-the-air activation message to the mobile telephone instructing the mobile telephone to switch to the side of the spectrum on which said desired service provider is operating.

8. The system of claim 6, wherein said means for commanding the subscriber's mobile telephone to switch to the side of the spectrum on which said desired service provider is operating, comprises means for sending a TDMA over-the-air activation message to the mobile telephone instructing the mobile telephone to switch to the side of the spectrum on which said desired service provider is operating.

9. The system of claim 6, wherein said means for commanding the subscriber's mobile telephone to switch to the side of the spectrum on which said desired service provider is operating, comprises means for sending a GSM USSD message to the mobile telephone instructing the mobile telephone to switch to the side of the spectrum on which said desired service provider is operating.

10. The system of claim 1 , wherein said means for determining whether a desired service provider of the subscriber operates on the side of the spectrum accessed by the subscriber comprises means for using information received from the subscriber to lookup service provider information in a database.

1 1. The system of claim 1, wherein said means for determining whether a desired service provider of the subscriber operates on the side of the spectrum accessed by the subscriber comprises means for determining whether a service provider accessed by the subscriber in the current geographic area is a desired service provider.

12. The system of claim 11, wherein said means for determining whether a service provider accessed by the subscriber in the current geographic area is a desired service provider comprises means for determining an identity of said accessed service provider from a mobile switch identification and means for comparing said identity of said accessed service provider with an identity of the desired service provider.

13. In a wireless communication method operating in a spectrum having at least two sides, each side having a service provider operating thereon, a method for providing service to a roaming subscriber in a current geographic area outside of a home area of the subscriber, the method comprising: determining whether a desired service provider of the subscriber operates on the side of the spectrum accessed by the subscriber; determining whether said desired service provider operates on any other side of the spectrum in the current geographic area; and providing service to the subscriber via the desired service provider if the desired service provider is available in the current geographic area.

14. The method of claim 1, wherein said step of providing service to the subscriber via the desired service provider comprises a step of notifying the subscriber that the desired service provider is operating on a different side of the spectrum.

15. The method of claim 14, wherein said step of notifying the subscriber comprises a step of sending a message to the subscriber indicating on which side of the spectrum said desired service provider is operating.

16. The method of claim 14, wherein said step of notifying the subscriber comprises step of sending an audio message to the subscriber notifying the subscriber that the desired service provider is operating on a different side of the spectrum.

17. The method of claim 14, wherein said step of notifying the subscriber comprises a step of sending an alphanumeric text message to the subscriber notifying the subscriber that the desired service provider is operating on a different side of the spectrum.

18. The method of claim 13, wherein said step of providing service to the subscriber via the desired service provider comprises a step of commanding the subscriber's mobile telephone to switch to the side of the spectrum on which said desired service provider is operating.

19. The method of claim 18, wherein said step of commanding the subscriber's mobile telephone to switch to the side of the spectrum on which said desired service provider is operating, comprises a step of sending a CDMA over- the-air activation message to the mobile telephone instructing the mobile telephone to switch to the side of the spectrum on which said desired service provider is operating. 20. The method of claim 18, wherein said step of commanding the subscriber's mobile telephone to switch to the side of the spectrum on which said desired service provider is operating, comprises a step of sending a TDMA over- the-air activation message to the mobile telephone instructing the mobile telephone to switch to the side of the spectrum on which said desired service provider is operating.

21. The method of claim 18, wherein said step of commanding the subscriber's mobile telephone to switch to the side of the spectrum on which said desired service provider is operating, comprises a step of sending a GSM USSD message to the mobile telephone instructing the mobile telephone to switch to the side of the spectrum on which said desired service provider is operating.

22. The method of claim 13, wherein said step of determining whether a desired service provider of the subscriber operates on the side of the spectrum accessed by the subscriber comprises a step of using information received from the subscriber to lookup service provider information in a database.

23. The method of claim 13, wherein said step of determining whether a desired service provider of the subscriber operates on the side of the spectrum accessed by the subscriber comprises a step of determining whether a service provider accessed by the subscriber in the current geographic area is a desired service provider.

24. The method of claim 1 1 , wherein said step of determining whether a service provider accessed by the subscriber in the current geographic area is a desired service provider comprises a step of determining an identity of said accessed service provider from a mobile switch identification and means for comparing said identity of said accessed service provider with an identity of the desired service provider.